This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 9900563-9 filed in Sweden on Feb. 18, 1999; the entire content of which is hereby incorporated by reference.
The present invention relates to communication in a cellular network and in particular a cellular network in which Localized Service Areas (LSAs) have been specified.
A cellular network operator can define one or more LSAs in the network, each LSA consisting of one or more cells.
The European Telecommunications Standards Institute (ETSI) is currently developing a new function called Support of LSA (SoLSA), which will enable the use of different tariffs, different access rights or services depending on the geographical location. The geographical location is based on physical radio resources. Typically, each subscriber will have a home and or office LSA in which the tariff is lower, or certain services are available which are not available to him in other cells.
The information about each subscriber""s allowed LSA or LSAs, is stored in the Subscriber Identity Module (SIM) card, and may be updated. When a subscriber is roaming in the network, an identity signal is received from each cell from which it is currently able to receive signals, and, if one of these signals comes from the allowed LSA, the subscriber camps on this cell. In some cases information about both the allowed LSA and each cell belonging to it is provided. For example, when a cell belongs to more than one LSA, it may be feasible to transmit only the cell identity instead of all possible LSA identities, which may reduce the paging capacity for the operator.
WO 98/30056 discloses a method and means for carrying out the method, by which a subscriber is informed about certain cells in a network. These cells may be defined as preferred cells, e.g. with call charges below the normal tariff. However, the disclosed method does not take into consideration possible occurrence of cell identifies and LSAs, both stored on a SIM-card. As a consequence of this, each subscriber must be provided with a required list of cell identities, whereby more network capacity is occupied than if only the changes in LSAs are transmitted. Moreover, no check can be made of whether changes have been made in the LSA arrangement, e.g. due to current cell planning.
Each operator can choose if only LSA identity or both cell identity and LSA identity is to be stored on the subscribers"" SIM cards. In the case where both cell identity and LSA identity are stored a problem may arise when cells are added to, or removed from an LSA. The information on the SIM card will then be incorrect, and must be updated. Two ways of updating the information have been discussed: The information can be transmitted through the air interface from a Service Management Centre (SMC) in the network using the Short Message Service (SMS) or Unstructured Supplementary Subscriber Data (USSD) service available in the network, or the subscriber""s SIM card can be returned to the operator and updated or exchanged.
Updating the SIM card from the SMC requires manual work to identify the SIM cards that are to be updated and to send out the SMS or USSD messages and the manual establishment of a connection to each mobile terminal that is to be updated. Returning the SIM card to the operator by post is time consuming and requires even more manual work. An application of SMS is the SIM data download feature, which is used to update SIM cards.
It is an object of the present invention to provide a simplified way of ensuring that each subscriber always has the correct information regarding his/her allowed LSA.
This object is achieved according to the invention by a method in a cellular telecommunications network in which at least one Localized Service Area, LSA, has been specified, each LSA comprising one or more cells, said method comprising the following steps:
determining if information regarding an LSA has been changed;
identifying at least one subscriber belonging to this LSA;
transmitting change information to said at least one subscriber belonging to the LSA to update information on a SIM card held by this subscriber.
The object is also achieved according to the invention by a node in a cellular telecommunications network said network comprising at least one Localized Service Area, LSA, has been specified, each LSA comprising one or more cells, said node being characterized in that it comprises
first and second storage means comprising information about the relationship between at least one LSA in the network and the cells belonging to it;
third storage means comprising information about the subscribers belonging to said at least one LSA;
control logic for determining when information regarding an LSA has been changed;
function means for effecting the transmission of change information to at least one subscriber in dependence of the contents of said first, second and third storage means.
The method and node according to the invention ensure that the LSA and cell identity information found on each subscriber""s SIM card is always correct and updated, with no manual work required.
According to a preferred embodiment the method further comprises the step of determining if the subscriber belonging to the LSA needs the update information for the type of change made and transmitting update information only if there is such a need.
This may be determined by means of an indicator set for each LSA, showing if cell identity information is stored on the SIM card. The node in this case comprises control logic for determining, on the basis of the indicator, if the change information needs to be transmitted to subscribers in this LSA.
This reduces the amount of information that has to be transmitted through the air interface, since in some cases only SIM cards having both cell identity and LSA identity information need to be updated.
Preferably, the node also comprises function means for effecting the transmission of update information to a home location register in the network.
In a preferred embodiment said node is a base station controller and the storage means are implemented in or in connection to the base station controller. This is feasible because the base station controller can easily establish connections both to mobile terminals and to the HLR.